It doesn't really have to. In fact, this doesn't need to be an issue at all: if the biblical literalists don't believe some aspects of science, nobody would give them a hard time. The fundamentalist hierarchy turned it into an issue by prosecuting school-teachers (starting with one John Thomas Scopes) for teaching science in science class; by making it illegal to tell the truth. It's not because they were afraid anybody force something on them; it's that they refused to relinquish control over the minds of their children. They brook no challenges to their absolute power.
There is very big money in keeping people pregnant, barefoot, ignorant and frightened. It's no accident that very devout nations have a lower standard of living of living than progressive ones.
The leechocracy made it political.